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Feature Article

Cerebral aneurysms and subarachnoid haemorrhage: avoiding the diagnostic pitfalls

Nicholas Little, Heath French
OPEN ACCESS

Endovascular therapy

The greatest change in the care of patients with this condition in recent times is the emergence of endovascular therapy as the dominant modality for treating ruptured cerebral aneurysms (Figure 2).29 The use of different embolic material and coils, along with stents and technical tricks of repair such as balloon-assisted coiling, have rapidly changed the deployment of endovascular therapy.48

Dedicated neurointerventional radiologists are now working in large centres and repairing the majority of ruptured aneurysms.48

Microvascular repair

Microvascular repair (surgical aneurysm clipping) remains an important modality for lesions unfavourable for endovascular intervention.29,49 Unsuitability for coil repair often relates to the ratio of the fundus to the neck of the lesion in locations where the use of stent or balloon assistance for the coiling may be inappropriate or unsafe.49 The most common location where coiling is not favoured is the middle cerebral artery bifurcation.94

Repair of a ruptured carotid bifurcation aneurysm is discussed in the case study (Box and Figures 1a and b).

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Open surgery

Open surgery may also be used where there are associated surgical benefits, such as removal of intracerebral clot.2

Treatments compared

In general, endovascular therapy has lower upfront risk than other treatments, and is without the associated morbidity of craniotomy (brain retraction, wound, access risk).29 It does, however, have less durability overall, and also a greater possibility of persistent/recurrent aneurysm necks (filling of the aneurysm where it pouches out from the vessel wall), which present an ongoing risk of haemorrhage, although the magnitude of that risk overall and in the previously ruptured versus the unruptured cohort is not well known.28,50 Securely coiled aneurysms that are stable after two years rarely re-rupture.50

A relevant factor in stent-assisted repair of aneurysm is that the patient usually requires indefinite antiplatelet therapy.51 This and issues of durability will become more clear as our longitudinal experience with this therapy improves with time.

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The ideal therapeutic scenario is where a balance and good working relationship exists between neuroradiologists and neuro­surgeons. Care decisions should not be based on treatment availability in a condition such as this, and collaboration is vital; however, access limitations to endovascular care can influence intervention decisions.49 There are frequent occasions where both coiling and clipping may be applied, either as planned adjuvants or in cases of failure of one or other.

In the presented case study, the anatomy of the aneurysm was such that simple coiling was not possible and stenting/­coiling was thought to be higher risk than microsurgical repair.

Conclusion

Cerebral aneurysms remain a diagnostic and therapeutic challenge. Although SAH can be excluded in most patients with headache by simple history taking, in those where doubt remains (e.g. when the haemorrhage is low volume and does not show on CT imaging) the consequences of failure to diagnose need to be weighed against the inconvenience and possible morbidity of further investigation.

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When an aneurysm has been diagnosed, the decision to treat and the mode of treatment to use has become multidisciplinary in a way analogous to that in many other medical conditions. This has led to better outcomes and the emergence of specialised neurovascular centres. MT

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